240 KEY AND FLORA 
pollination. The genera of the northern United States are 
divided into two suborders: I. TupuLiFLtor», corolla of 
the bisexual flowers tubular and 5-lobed; I. Licuniritora, 
corollas all strap-shaped and flowers all bisexual. 
A F 
Fic. 30. Akenes with various types of pappus 
A, Rudbeckia, pappus wanting; B, Cichorium, pappus a crown of fine scales; 
C, Coreopsis, pappus of 2 small scales; D, Heleniuin, pappus a crown of 
conspicuous scales; EF, Cirsium, pappus a tuft of plumose hairs; F’, Lac- 
tuca, pappus borne on a long beak 
I. TUBULIFLORE ! 
Corollas some or all of them tubular. 
Rays white, pink, or purplish. 
Rays many; akenes flat; pappus wanting; low herbs. Bellis, I 
Rays many; akenes cylindrical or winged, grooved; pappus 
wanting; 
Ss 
Rays many; akenes flat; pappus of an outer row of minute 
tall herbs or shrubby. Chrysanthemum, X 
scales and an inner row of delicate bristles. Erigeron, II 
Rays many; akenes cylindrical or ribbed; pappus wanting ; 
strong-scented, branching herbs. Anthemis, IX 
Rays few. Achillea, VIII 
1The characters in this key are not necessarily true of all species in the 
genera referred to, but only of those described below. 
